Not to worry. Usually, if there's a sizable demand - people make it happen. Does that mean every single game will be playable 10 or 20 years from now? No. But that's always been true - as some games just don't work well with modern hardware.

I have to say I think any real danger of not being able to play these games in the future is pretty negligible - and I honestly wouldn't have the time available to replay very many at any rate.

My concern about the future is not having the free time to play all the games I'd want to (and do all the things I'd want to do). It's certainly not that there won't be enough things for me to do.